1. Field of the Invention
The present invention relates to a projection device capable of effectively performing the light utilization, and more particularly to utilize polarized beam components and reflective components to control the light polarization such that the dissipation and attenuation of light can be further reduced during the transmission process to enhance the utilization efficiency of light.
2. Description of the Related Art
A light emitting diode (LED) is a semiconductor component. Since LEDs have advantages of high efficiency and long service life, currently the LEDs are widely applied in many different fields. For example, the LED can be applied to a projection display device to provide a light source required for projection.
With respect to a conventional projection display device, to reduce etendue effect and effectively utilize the light source, a polarization conversion system (PCS) is disposed inside the conventional projection display device. The PCS is also called beam splitting component that is divided into a reflective PCS and absorption PCS for converting beam polarization direction into S-wave or P-wave so as to increase the light utilization.
With reference to FIG. 1 for a schematic diagram of a light source device of conventional projection equipment is depicted. As shown in FIG. 1, the light source device 1′ divides a non-polarized beam emitted by a light source emitter E′ into two polarized beams L1′, L2′ that are perpendicular to each other. The light source device 1′ includes a polarized beam splitting component 11′, two reflective micro-displays 12′, 13′, an illumination lens set 14′ and a projection lens set 15′. When the light source emitter E′ emits the non-polarized beam L′, the non-polarized beam L′ is concentrated by the illumination lens set 14′ to reach the polarized beam splitting component 11′. At this time, the non-polarized beam L′ is divided by the polarized beam splitting component 11′ into two polarized beams L1′, L2′ that are perpendicular to each other. Next, the two polarized beams L1′, L2′ are respectively projected to the two reflective micro-displays 12′, 13′ and reflected through the polarity of the two reflective micro-displays 12′, 13′, wherein the polarized beam L1′ directly passes through the polarized beam splitting component 11′ to reach the projection lens set 15′. The polarized beam L2′ is reflected to the projection lens set 15′ through the polarized beam splitting component 11′. Finally, the two polarized beams are projected to form images via the projection lens set 15′.
With the foregoing depiction, the structural design of the light source device 1′ is quiet simple, and the light source device 1′ has the following advantages:    1. The light source device 1′ utilizes the polarized beam splitting component 11′ to polarize and convert the beam polarization direction so as to increase the light utilization.    2. In addition, the non-polarized beam L′ is divided into the two polarized beams L1′, L2′ that are perpendicular to each other and transmitted via two different paths and outputted to the projection lens set 15′ for projecting and imaging. Such the foregoing manner does not only control the beam strengths of two paths, but also control the polarization state of beams at two paths simultaneously. By incorporating a liquid crystal shutter glasses, a stereoscopic effect can be achieved for visual perception of a viewer.
The foregoing technique still has the following shortcomings although the light source device 1′ has many advantages.    (A) Low light utilization: to reduce etenude effect and effectively use the light source, the conventional projection display device is realized by the beam splitting components. However, in actual operating, the beam is not really and completely polarized after passing through the beam splitting components. Consequently, the light utilization is absolutely low. Further, no additional room for disposing a beam polarized purification component between the beam splitting component and the reflective micro-displays of the conventional projection display can offset the beam that is not completely polarized yet. Although there are additional rooms to dispose beam polarized purification component, its optical property is also influenced by incident angles. Thus the uniformity of the illumination is affected well; and    (B) The brightness of polarized beams at different paths is unable to be controlled. As shown in FIG. 1, the beam is divided into the polarized beams L1′, L2′ at different paths after entering the polarized beam splitting component. The two polarized beams may have difference on strength due to quality of the beam splitting components and the lens sets. The expression of final stereoscopic imaging may be influenced as well.
Therefore, for a light source device of conventional projection equipment, the foregoing shortcomings must be overcome to effectively perform the light utilization, and the beam strength at different paths can also be regulated.